1. Field
The present inventions relate generally to waterproof enclosures for acoustic elements such as microphones and speakers, and may be described in the context of microphones used with a sound processor of a cochlear implant system; however, it should be understood that the inventions have application in other apparatus that include acoustic elements, such as microphones and speakers, and are exposed to moisture.
2. Description of the Related Art
Many acoustic devices are inherently sensitive to moisture and are easily damaged by water. Any apparatus that requires a microphone, speaker or other acoustic device, and needs to be water resistant or waterproof, must address this weakness. In the exemplary context sound processors and microphones, commercially-available microphones that offer protection from water are generally either too large or suffer from poor performance under the conditions that patients would like to use their sound processors. Waterproof microphones implementing sealed acoustic chambers are large and complex, and may have an undesirable frequency response, making them impractical for use with cochlear implants. Water-repellent membranes that prevent liquid water ingress but allow vapor-phase transport and have minimal impact on sound quality may be sufficient for splash-protection, but they cannot provide protection in water immersion or long-term protection from water vapor. Other problems inherent in previous designs include holes, recesses, and cavities that fill up with water and take a long time to dry. Previous designs using silicone barriers are subject to the problem that silicone absorbs water and releases it very slowly, and also that silicone tends to dampen the sound. A microphone can be sealed by dipping it in a polymer, but these designs are not feasible in a small form factor microphone, and typically suffer from poor acoustic performance.